A known technique displays a road map three-dimensionally on a display device. In such a technique, a route including multiple roads connected in-line is sometimes hidden behind structures such as a building and topography shown three-dimensionally; thereby, the road may not be confirmed. To address such a disadvantage, the following techniques for processing graphics of structures have been proposed as follows: a technique for reducing height of buildings around the route; and a technique for drawing buildings by use of wire frames (for example, see Patent Documents 1 to 5).    Patent Document 1: JP-H9-212083 A    Patent Document 2: JP-H9-318381 A    Patent Document 3: JP-2000-207577 A    Patent Document 4: JP-2000-304558 A    Patent Document 5: JP-2000-321974 A